Citations

e22124 Background: Therapeutic anti-cancer vaccine strategies have been effective in a broad range of preclinical tumor models, but clinical trials of vaccines in metastatic cancer patients have failed to show clinical benefit. We have previously shown that patients with stage IV melanoma have systemic immunosuppression including elevated plasma levels of immunosuppressive cytokines and impaired DTH responses to recall antigens. Patients with stage IV melanoma also have elevated circulating levels of the vascular growth factors vascular endothelial growth factor A (VEGF A) and placental growth factor (PlGF). Based on these observations, we have hypothesized that vascular growth factors such as VEGF and PlGF mediate systemic immunosuppression. Methods: FVB mice with established ANV6 transplantable breast tumors were bled, and plasma samples were assayed for VEGF, PlGF, and interleukin (IL)-10. Splenocytes taken from tumor-bearing mice were stimulated via the T cell receptor (TCR), and interferon gamma (IFN) production was measured. Splenocytes from normal mice were stimulated in the presence or absence of VEGF; IFN production was measured. Results: Compared with age- and sex-matched controls, tumor-bearing mice had elevated plasma levels of VEGF, PlGF, and the immunosuppressive cytokine IL-10 (see table ). Furthermore, splenocytes from tumor-bearing mice produced less IFN upon TCR stimulation than did splenocytes from control mice. Finally, normal mouse splenocytes produced less IFN when stimulated in the presence of VEGF than in its absence (70.2 ± 37.2 vs. 260.0 ± 130.9 pg/ml). Conclusions: We have shown that mice with advanced tumors exhibit both elevated levels of vascular growth factors and systemic immune inhibition. We have also shown that VEGF leads to impairment of immune function in normal splenocytes. Taken together, these results suggest that excess vascular growth factors may mediate immunosuppression in animals with advanced tumors, which may in turn impair anti-tumor vaccine efficacy. [Table: see text] No significant financial relationships to disclose.

AbstractBackgroundBenign capsular nevi (BCN) are not infrequent in sentinel lymph nodes (SLN) of patients with melanoma. Their prognostic significance is unknown and the literature is limited. This study evaluated the clinical significance of incidentally found BCN in these patients.MethodsA multi‐institutional retrospective review of patients undergoing SLN biopsy for cutaneous melanoma between 2000 and 2016. Patients were divided into the following groups: (a) negative SLN and no BCN, (b) negative SLN and presence of BCN, (c) positive SLN seen only on immunohistochemistry (IHC), and (d) positive SLN via hematoxylin and eosin (H&E). Outcomes measured were overall survival and any recurrence.ResultsA total of 1253 patients were identified (group 1 = 978, group 2 = 56, group 3 = 32, and group 4 = 187). Fifty‐seven percent were male and the mean age was 59.3 years. BCN was identified in 77 patients (6.2%), of which the majority was in the node‐negative group (72%). Multivariable analysis showed that BCN was associated with lower recurrence rates, though not statistically significant (hazard ratio [HR] = 0.5; P = .06). IHC‐ and H&E‐positive SLNs were associated with a higher risk of recurrence (HR = 2.4; P = .02 and 2.0, P < .0001, respectively).ConclusionPatients with BCN and negative SLN had lower recurrence rates than patients with negative SLN and no BCN. Our data suggest a possible protective effect against recurrence.

e22052 Background: Metastatic Uveal Melanoma (MUM) is a rare tumor with poor prognosis following development of liver metastasis. We hypothesized that patterns of metastasis in Uveal Melanoma correlate with clinical outcomes. Methods: We retrospectively reviewed patients with MUM at Mayo Clinic, Rochester from January 1999 to August 2019. Patients were stratified into two groups based on the pattern of hepatic and pulmonary metastasis at the time of diagnosis of metastatic disease: Group 1 (≤5 liver metastasis or lung metastasis) and Group 2 ( > 5 liver metastasis without lung metastasis). Baseline characteristics were compared between both groups. Survival analysis was performed using the Kaplan Meier method. Univariate and multivariate analysis were performed for Overall Survival (OS). Results: 147 patients were included in the study (n = 67 Group 1; n = 80 Group 2). In Group 1, 49/67 patients presented with ≤5 liver metastasis and 18/67 had lung metastasis without liver metastasis. Median OS for Group 1 was significantly longer than Group 2 (38 vs. 15 months; p < 0.0001) (Table). On univariate analysis, predictors for OS were: Pattern of Metastasis, ECOG PS > 0, Time to metastasis > 60 months, and Surgical metastatectomy. Pattern of Metastasis was an independent predictor for OS in a multivariate model that included these predictors (p = 0.0004). Group 1 patients were more likely to undergo surgical metastatectomy compared to group 2 (21.5% vs. 1.3%; p < 0.0001). Interestingly, the median time to metastasis from diagnosis of UM was significantly longer for Group 1 as compared to Group 2 (67 vs. 24.5 months; p < 0.0001). Conclusions: Limited (≤5) liver metastasis or lung metastasis (without liver metastasis) at diagnosis predict favorable clinical outcomes in MUM. The occurrence of such metastasis following a significantly longer time from primary diagnosis suggests the existence of a distinct sub-type of metastatic disease with relatively indolent behavior. [Table: see text]

e22020 Background: The combination of nab-paclitaxel (NP) and bevacizumab (BEV) in patients with MM has shown promising clinical activity. AB160 is a 160 nm nano-immunoconjugate of NP nanoparticles non-covalently coated with BEV for targeted delivery into high VEGF expressing tissues. Preclinical data showed that AB160 improved tumor targeting/ tumor inhibition more than NP followed by BEV. Methods: A 3+3 phase I trial was conducted in patients (pts) with MM who had prior systemic treatment for metastatic disease to determine the maximum tolerated dose of AB160 administered intravenously on days 1, 8 and 15 of a 28-day cycle. Dose level 1 (DL1) was 125 mg/m2 NP /50 mg/m2 BEV. Dose limiting toxicities (DLT) included grade (G) 4 neutropenia or anemia, PLT < 25,000, serum creatinine ≥ 2 times baseline, G2-4 neurologic toxicity or G3-4 non-hematologic toxicities. Tumor evaluations (RECIST) were conducted every 8 weeks. Treatment continued until progression or intolerability. Results: 21 pts (11 ♀) aged 36-78 years old were enrolled. One of the first 3 pts on DL1 developed a G2 colonic perforation; this was considered a DLT. One of the next 3 pts on DL1 had a DLT: G4 neutropenia. Of the 3 pts on DL-1 (100 mg/m2 NP/40 mg/m2 BEV), 2 had no DLTs and 1 died of sepsis after C1D1 dose. Enrollment was suspended until an amendment modifying the eligibility criteria was approved by the IRB. The trial reopened. One of the 4 pts on DL-1 and 1 of the 5 pts on DL1 had a DLT: G3 pain and G3 fatigue, respectively. Enrollment ended after 2 of the 3 pts on DL2 (150 mg/m2 NP/ 60 mg/m2 BEV) developed G4 neutropenia. Thus, MTD is DL1. A median of 3 cycles was administered. Treatment ended due to progression (9), intolerability (9), refusal (2) and death (1). There were no objective tumor responses. Common G3-4 toxicities were: neutropenia (33%) and thromboembolic events (19%). Conclusions: AB160 was found to have insufficient clinical benefit in patients with previously treated MM to justify further development. However, parallel phase I testing in gynecologic cancers suggests clinical benefit (abstract #300225). Clinical trial information: NCT02020707.

e18097 Background: AB160 is a 160 nm nano-immunoconjugate consisting of nab-paclitaxel (NP) nanoparticles non-covalently coated with bevacizumab (BEV) for targeted delivery into tissues expressing high levels of vascular-endothelial growth factor (VEGF). Both taxanes (GOG-0129C, GOG-0126R, GOG-0127V) and BEV (GOG-0229E, AURELIA, GOG-0227C) have demonstrated clinical activity in previously treated metastatic endometrial cancer (EC), ovarian cancer (OC), and cervical cancer (CC), respectively. Methods: A 3+3 phase I trial was conducted in patients with EC, platinum-resistant OC and CC who had prior systemic treatment for metastatic disease to determine the maximum tolerated dose of AB160 administered intravenously on days 1, 8 and 15 of a 28-day cycle. The starting dose level (DL1) was NP at 125 mg/m2 with BEV at 50 mg/m2. There were 2 higher dose levels: DL2 (NP at 150 mg/m2 with BEV at 60 mg/m2) and DL3 (NP at 175 mg/m2 with BEV at 70 mg/m2). Dose limiting toxicities (DLT) included grade (G) 4 neutropenia or anemia, PLT < 25,000, serum creatinine ≥2 times baseline, G2-4 neurologic toxicity or G3-4 non-hematologic toxicities. Disease evaluations were conducted after every 2 treatment cycles using RECIST criteria. Patients were treated until disease progression or intolerability. Samples were collected for pharmacokinetic (PK) studies. Results: Nine women 41 – 74 years of age (median 57) have enrolled (5 with EC and 4 with OC); data are available for the first 8. No DLTs have been observed among the 3 women enrolled on DL1, 3 women on DL2, and 2 women on DL3. All 3 patients on DL3 continue on treatment. The other 6 patients have discontinued due to adverse reactions (3), progression (2), and patient choice (1). The median number of cycles administered is 6 (4-14). The most common severe (G3/4) toxicities include neutropenia (37.5%) and leukopenia (25%). There have been 5 partial responses (62.5%): 1 on DL1 and 2 each on DL2 and DL3. PK evaluation is pending. Conclusions: AB160 therapy is safe and demonstrates promising clinical activity in patients with previously treated metastatic gynecologic malignancies. Further clinical testing is being pursued in this patient population. Clinical trial information: NCT02020707.

6040 Background: FRα is overexpressed on > 90% of high-grade EOC. We conducted a randomized double-blind multicenter phase II clinical trial to evaluate the safety and efficacy of TPIV200 (a multi-epitope FRα peptide vaccine admixed with GM-CSF adjuvant) versus GM-CSF alone as a control in patients with stage III-IV high-grade platinum-sensitive epithelial ovarian, fallopian tube, or primary peritoneal carcinoma in first complete or partial remission, irrespective of baseline level of FRα expression. Methods: Patients with stage III-IV high-grade serous, high-grade endometrioid, carcinosarcoma or poorly differentiated EOC who had previously completed standard upfront therapy without evidence of disease progression and who were within a year of last platinum were randomized 1:1 to intradermal vaccination of TPIV200 versus intradermal GM-CSF alone. The vaccination period included 6 administrations of the study drug at 4-week intervals. Up to 6 booster vaccinations at 12-week intervals were permitted for patients who did not have disease progression. AEs were assessed using CTCAE. Tumor response was assessed via RECIST every 12 weeks. The primary endpoint, progression free survival (PFS), was calculated from date of first vaccination to the date of progression, death or study termination. Results: Of 120 patients randomized, 63 (53%) were treated on the TPIV200 arm. The median age at study entry was 63 years (range 37-88). AEs were generally mild. Injection site reaction was more frequent in the TPIV200 (63%) versus GM-CSF arm (39%). The other most common AEs, abdominal pain (25%) and fatigue (23%), were comparable in both arms. At study termination with a median follow-up of 15.2 months (range: 1.2-28.3 months), 68 of 119 intention-to-treat patients had progressed (55% in the TPIV200 arm and 59% in the GM-CSF arm). The median PFS was 11.1 months (95% CI: 8.3-16.6 months) and there was no statistically significant difference in median PFS between the arms (10.9 months with TPIV200 versus 11.1 months with GM-CSF, HR = 0.85 [upper 90% CI = 1.17]). Conclusions: Although TPIV200 had a manageable safety profile, the study was terminated for futility after the planned interim analysis. Future development of FRα-targeted therapy will likely focus on the careful selection of patients whose cancers show high FRα expression. Clinical trial information: NCT02978222.

6010 Background: The efficacy of treatment for recurrent endometrial cancer (EC) remains limited. Vascular endothelial growth factor and inflammatory chemokines are proangiogenic factors and immune modulators involved in immune suppression. Reprogramming the tumor microenvironment by combining antiangiogenic and immunotherapy (IO) could enhance antitumor responses. Methods: A 2:1 randomized phase 2 trial compared the combination of cabozantinib and nivolumab (Arm A) versus nivolumab (Arm B) in recurrent EC. Primary endpoint was progression free survival (PFS) assessed by RECIST 1.1 (NCT03367741). Women with recurrent measurable EC were eligible. There were no limits on prior therapy, but at least one prior platinum-based chemotherapy was required. Patients (pts) were stratified according to MSI status and assessed by CT every 8 weeks. Cabozantinib was given at 40 mg daily (Arm A) and nivolumab at 240 mg, on D1 and D15 of a 28-day cycle for 4 cycles, followed by 480 mg every 4 weeks (Arms A & B). Pts with carcinosarcoma or prior IO were enrolled in an exploratory cohort and received combination treatment (Arm C). A baseline biopsy was required for all pts. CyTOF analysis was performed on fresh biopsies. Results: 76 evaluable pts were enrolled (Arm A: 36, Arm B: 18, Arm C: 9 carcinosarcoma, and 20 post IO including 7 pts crossed over from Arm B). 55% of pts had received ≥3 prior lines of therapy. Two pts were MSI high in Arm A and none in Arm B. The Kaplan-Meier estimated median PFS was 5.3 (95% CI: 3.5-9.5) months in Arm A and 1.9 (95% CI: 1.6-3.8) months in Arm B, with a log-rank p = 0.07, which met the significance level of 0.1 used for sample size calculation. Objective response rate (ORR) was 25% for Arm A and 16.7% for Arm B; stable disease (SD) was seen in 44.4% vs 11.1%, respectively. Clinical benefit (ORR+SD) was significantly higher in arm A vs B (p < 0.001). In Arm C-carcinosarcoma, one patient had a partial response (11.9 months duration) and four SD. In Arm C-prior IO, six pts responded and eight had SD. The most common related AEs in Arm A were diarrhea (47.2%), elevated liver enzymes (44.4%), fatigue (38.9%), anorexia, hypertension, and nausea (30.6%), mainly grade 1/2. Preliminary CyTOF analysis across treatment arms identified multiple immune subsets for further interrogation including activated CD8+ and CD4+ T cells. Conclusions: Cabozantinib plus nivolumab demonstrates improved PFS compared to nivolumab in heavily pre-treated women with recurrent EC. In-depth CyTOF analysis of the tumor microenvironment to identify predictive immune biomarkers of response is ongoing. Clinical trial information: NCT03367741.

Management of PD-1 blockade resistance in metastatic melanoma (MM) remains challenging. Immunotherapy or chemotherapy alone provides limited benefit in this setting. Chemo-immunotherapy (CIT) has demonstrated favorable efficacy and safety profiles in lung cancer. Our pre-clinical study showed that in MM patients who have failed PD-1 blockade, the addition of chemotherapy increases CX3CR1+ therapy-responsive CD8+ T-cells with enhanced anti-tumor activity, resulting in improved clinical response. Here, we examined the clinical outcomes of CIT in MM patients after PD-1 blockade failure and the treatment-related changes in CX3CR1+ therapy-responsive CD8+ T-cells. We reviewed MM patients seen between January 2012 and June 2018 who failed anti-PD-1-based therapy and received subsequent CIT, immune checkpoint inhibitors (ICI) or chemotherapy alone. Overall survival (OS), objective response rate (ORR), event-free survival (EFS), and toxicities were assessed. Among 60 patients, 33 received CIT upon disease progression on PD-1 blockade. At a median follow-up of 3.9 years, the CIT group had a median OS of 3.5 years [95% confidence interval (CI) 1.7–NR] vs. 1.8 years (95% CI 0.9–2; P = 0.002) for those who received subsequent ICI (n = 9) or chemotherapy alone (n = 18), with ORR of 59% vs. 15% (P = 0.0003), respectively. The median EFS was 7.6 months (95% CI 6–10) following CIT vs. 3.4 months (95% CI 2.8–4.1; P = 0.0005) following ICI or chemotherapy alone. Therapy-responsive CX3CR1+CD8+ T-cells showed dynamic increase with successful CIT. CIT showed favorable clinical outcomes and acceptable safety profile in PD-1 blockade-resistant patients. CX3CR1+CD8+ therapy-responsive T-cells can be potentially used for monitoring disease response to CIT.